Magnatek Converter Problem Solved
On Friday, I took my spare RV, a 2002 R-Vision Class B, to the Christmas parade and found a parking place where the DW could view the parade from the warm confines of the RV.
When I shut the genset off, I noticed that the heat and water pump still worked but the interior lights did not. Checked the fuses, salesman switch, etc. and all were good.
On Saturday, started to check things out starting with the battery (12.7 v so good) and the solenoid. Found a blown fuse at the solenoid but that turned out to be for the emergency start solenoid.
Using my PowerProbe (get one for Christmas if you don't have one!), I checked the wiring on the leads to the fuse panel of the Magnatek 7300 Series Model 7345. I finally noticed a ground bar on the side of the cabinet that was a common ground for the lights. When the RV was plugged in, the ground bar was grounded/negative as expected and lights worked. When the RV was unplugged and on battery power, the ground bar gave me a 12.7v POSITIVE charge. With 12.7v on both the positive side AND the negative side, the lights would not work because there was no current flowing. However, when I applied a negative with my PowerProbe, viola the lights went ON!
To make a long story short, I traced a ground wire from the bar to the Magnatek. Again, applying a negative with the PowerProbe to the ground wire, the lights went on. So one of the relays in the Magnatek was not flipping over to supply a ground for the lights. Evidently, the pump and heater don't rely on that ground.
A new Magnatek is around $300 so I went with a much cheaper fix since the RV is 13 years old. I rigged an ON/OFF switch from chassis ground to the ground lug in the Magnatek. When the RV is plugged in, the switch stays off as the ground wire is good. When using battery, I flip the switch to ON to use the chassis ground and the lights go on!
I saw some similar problems listed on the forum but none specifically dealt with losing partial 12 volt systems. Hopefully this will help someone in the future!
Tom and Katharine
'07 Winnebago Tour 40TD, 400hp Cummins
RVing for 19 years & 150,000+ miles